Rob Arnold's YouTube channel is a great source of knowledge and experience from an underrated metal guitarist. The Chimaira member is getting ready for a reunion show with the Cleveland band at the Inkarceration Festival in Mansfield, Ohio on 19 July (and he's been talking about his streamlined rig including a Fender Tone Master in his other videos) but he's keeping up with his tutorial videos.
In his most recent lesson he's teaching a beginner-friendly run-through of classic metal riffs including Black Sabbath's Iron Man. We say beginner-friendly because Rob offers an alternate easier single-string way to play each riff which is really useful for players starting out but wanting to play songs they love.
We hope Rob will continue making videos like this and we'd recommend you check out his YouTube channel for more.